Belgian officials say at least 25 people have been killed in a collision between two commuter trains outside Brussels.

The crash took place in a suburb of Brussels, when two morning commuter trains collided outside the station in Hal.

The town's mayor, Dirk Pieters, offered an early estimate of the casualties, saying about 20 people are dead. He said the initial numbers were based on reports from police and firefighters.

The accident took place in snowy conditions.

One passenger contacted by French radio described the crash.

The passenger said the collision was brutal and the train he was on had been going at full speed. He said the cars in front of him had been affected and as he descended from the train he saw four dead passengers. He said he did not want to imagine the state of the other passengers in the affected train cars.

Images on Belgium television showed the first car of each of the trains pushed up into the air and off the tracks. A spokeswoman for Belgium's SNCB rail service estimated the crash had left dozens of people seriously wounded.

Following the accident, some local rail service, along with traffic on the high-speed international trains Thalys and Eurostar, was interrupted or suspended.